Two basically different types of capsules for pharmaceutical preparations are commonly used: a "hard-shell" capsule and a "soft-shell" capsule. Conventional hardshell capsules are formed mostly of gelatine, have a body part (lower portion) and a cap (upper portion) telescopically engaging the body part, and contain pharmaceutical preparations in solid form, such as powder or pellets. Conventional soft-shell capsules are formed of gelatin and plasticizers, and usually contain pharmaceutical preparations in liquid form, such as suspensions, pastes and oils. The two types of capsules, which are intended predominantly for oral administration, are filled in different manners.
Thus, the hard-shell capsule can be filled by the manufacturer of the pharmaceutical preparation himself, for instance by filling the body part with the solid pharmaceutical preparation, then telescopicaly fitting a cap onto the body part, with any trapped air being vented through a gap between the body and cap parts, then if required, providing the capsule with a band sealling the free end of the cap with respect to the outer wall of the body part.
In contrast, the filling of conventional soft-shell capsules with liquid pharmaceutical preparations is relatively complex as the soft-shell capsules are formed only at the time of their being filled, from two joined halves enclosing between them the liquid pharmaceutical preparation. These operations require a specific technique and are usually not performed by the manufacturer of the pharmaceutical preparation himself, which causes considerable disadvantages, also in view of the high demands made on quality and safety that have to be observed in the manufacture of finished medicament capsules.
Until now, so far as we are aware, there has been no simple process for filling medicament capsules with liquid pharmaceutical preparations at the site of manufacture of the pharmaceutical preparation assuming that this site is different from the place of manufacture of the capsule parts. In the case of soft-shell capsules, this cannot be realized in view of the complex technique. In the case of hard-shell capsules, sealing problems are encountered because the liquid pharmaceutical preparation penetrates into the space between the external surface of the body part and the internal surface of the cap and it is necessary to protect against such leaking by providing a band around the capsule. In practice, there is need not only for capsules filled with liquid pharmaceutical preparations, but quite generally for capsules filled with any liquid or viscous materials, for example, liquid or pasty materials. Such materials can be, for example, stain-removing agents, solvents, volatile oils, liquid spices, silicone oils or chicken fat. Hard-shell capsules are particularly advantageously used for containing materials that must be carefully stored (e.g. air-tight), must remain ready for use, and are required in small amounts, i.e. in portions. The materials may, for example, become thinly liquid when they are heated and thickly liquid or even pasty when they are cooled.